Distillation of tar, etc.



Jan. 16, 1934.- s. P. MILLER DISTILLATION OF TAR, ETC

-Filed Aug. 30. 1929 5 Sheets-Sheet vl w mv ATTORN EYS Jafl- 16, 1934-s. P. MILLER DISTILLATION OF TAR, ETC

Filed Aug. so

, 1929 5 Sheets-Sheet 2 Mln.

Jan. 16, 1934, s, P, WLLER 1,944,129

DISTILLATION OF' TAR, ETC

INVENTOR @www v ATTORN EYS Patented Jan. 16, 1934 UNlTlEo STATES;

1,944,129 y nrs'rnmArIoN or fran. nrc.

Stuart Miller, Englewood, Nfl., assignor to The. Barrett Company, NewYork N. Y., a corporation ot New Jersey Application August' so, 192s.serial Nn. 389,345

14 claim. (o1. zoo-39) This invention relates to the recovery ofbyproducts from hot coke oven gases according to which the gases from abattery of coke ovens are fractionally cooled to produce'a heavier tar.

6 and a lighter tar and the lighter tar is distilled to produce cleandistillate. The distillation of the lighter tar may be carried on invarious ways and various products may be produced, The invention relatesmore particularly to the recovery of a, heavier tar fraction which issuitable for use in road construction without distillation and also alighter tar or tarry oil fraction which on distillation and extractiongives a high yield of tar acids.v The invention includes both theprocess and 'apparatus for carrying it out.

According to the ordinary method of operating a coke oven plant, the hotcoke oven gases from the various ovens are collected in a lgasvcollector main and subjected to partial cooling during which a heavytar is separated from the gases and the resulting partially cooled gasesare passed to a condensing system where lighter tar or tarry oils areseparated from the gases'.l

The heavy tar from the collector main and tarry oil from the condensersare ordinarily blended tars may be formed, as, for example, a. tarwhichseparates from the gases inthe crossover main. This tar is-ordinarilyblended with the tarry oil obtained from the' condensers and the mixedtar' thus produced is blendedwith the heavy` tar from the collectormainto produce a total tar. 1 f

According to the present invention, the hotcok'e oven gases arefactionally cooled but the various tar fractions produced are collectedseparately and a lighter fraction is subjected toA 1 distillation toproduce `distillate oil and pitch.l

The cooling is preferably regulated to `yield a heavier tar which may beused directly as a road amount of spray used and the temperature of thespray are regulated to determine the extent to which the gases arecooled in the gas collector main andthus to control the amount of oilsthrown down'in the main and the meltingl point of the 'tar produced.

Instead of spraying the gases, the ygases may 5` be cooled by directcontact with a stream o'f a cooling medium which is caused to iiowthroughthe bottom of the collector main. This stream may be a mixture ofammonia liquor and tar orv a stream of tar only may be used. V'Ihere may70 besome distillation ofthe tar used for cooling the gases and thevapors thus produced'will-pass from the collector main with vaporsalready present in the gasesand on cooling composite oils will separatein the condenser.

The lcooling of the gases in the collector main may be accomplished bysprayingthe gases, andl simultaneously passing a stream o f a. coolingmedium through the bottom of the collector main. The cooling may merelyraise the ten. perature of the cooling medium, or volatilization ofapart of the cooling medium may result. For example. water may bedistilled where ammonia liquor either alone or together with tar, isused for vcooling the gases, or lower boiling. constituents of the tarmay be distilled where tar is employed as a cooling medium. 1v

After the gases leave the collector main they are further cooled andthis cooling may be a fractional cooling to' produce different tarfractions or a single tar may be produced by a single -stage cooling ofthe gases. The cooling may be in one or more indirect condensers ordirect cools ing. may be employed by bringing the gases into directcontact with ,water or ammonia. liquor.- Where desirable, reliuxing orothermeans forl obtainingsharp fractions of .tar or tarry oil may Y beemployed. I

The cooling in the collector main, regardless ofhow thecooling iseiected, is so regulated that the gases leave the collector mainat ahigher temperature'vthan ordinarily and the tar obtained fromthecollector main comprises constituents .of higher boiling range and iscomparatively free from the lower boiling constituents usually presentin such a tar. According to the preferred method of operation, thecooling is so regulated that'the tar produced may be used directly as -aroad tar or may be blended with other tars as above described to giveVroad tars of ldesired characteristics. The melting point of the tarobtained from the collector main may advantageously be in theneighborhood of 90 or 95 to 110 or 115 F. A method of preparing suchproducts as applied to coal distillation gases enriched in oilconstituents is described in my copending application Serial No.206,368, led July 13, 1927, which has matured into Patent No. 1,826,431.

As obtained from the collector main thevtar may be contaminated withammonia liquor, as, for example, in a main in which the gases are cooledby spraying with water or ammonia liquor. The water or ammonia liquoran'd tar are advantageously separated before the. use of the tar as aroad tar although the iinished road tar product may contain a smallamount of moisture. The tar produced in the collector main according tothis method of operating and water gas tar or gas house tar are readilymiscible, and they may be blended by directing a stream o f each of thetars into a storage tank and so directing the streams of the tars thatthey unite before hitting the surface of the blended material containedin the storage tank. Agitating means may be provided within the tank,where desirable. The tars may be blended at a somewhat elevatedtemperature and where this may readily be done, it is benecial.

Where a stream of tar is to be fed into the bottom of the collector mainas a part of the collector main operation, the gas house tar or watergas tar or other tar employed for blending with the tar from thecollector main to produce a road tar may be delivered directly to thecollector main. On passing through the main this tar will serve to coolthe gases, at least to some extent, and lower boiling point constituentsmay be volatilized from this tar although any considerable distillationof the tar in the collector main is not contemplated. By feeding watergas tar or gas house tar to the collector main in regulated amount, ablended pitch suitable i'or road purposes may be drawn off direct fromthe collector main and be used directly without distillation or furtherblending.

According to this invention the lighter tar or tarry oil separated fromthe gases subsequent to the initial vpartial cooling is distilled'. Thercondensers may be either direct or indirect condensers and the gasesmay be cooled to in the portion of this heavy tar may be blended withvthe tarry oil before distillation, or the heavy tar may be separatelydistilled.

According to the preferred form of carrying out this invention, thegases leave the collector main at a highertemperature than usual andtherefore the tarry oil obtained contains a higher percent of oils ofhigher boiling range than ordinarily. On distilling the tarry oil a highmelting point pitch, e. g., a pitch with a melting point of up to 350 F.or 400 F. or higher may be produced. An oil yield as high as or 90% maybe obtained, with a. correspondingly low yield ofhigh melting pointpitch.

The distillate is a distillate comprising oils of higher boilng rangeand may advantageously be blended directly with some undistilled tarryoil to produce a. composition-suitable for creosoting purposes. Byregulating the amount of tarry oil added to the distillate, the freecarbon content. of the' blended product maybe controlled.

The distillate may be collected as a single product and used for cleanAcreosote oil, although such an oil will ordinarily be lighter andcontain a larger percent of oils of lower boiling range than an oilobtained by the ordinary distillation of a total tar; by. carrying thedistillation to a pitch of high melting point, however, a creosote oilcomprising oils of higher boiling range may be obtained.

Instead of cooling the vapors in a single stage, two or more fractionsof clean oils may be obtained. Where a heavier oil fraction and alighter oil fraction are obtained, the lighter oil. containing arelatively high percentage of tar acids, may be extracted for therecovery of the tar acids and with or without the working up of thislighter fraction for naphthalene, the neutral oil remaining after theextraction of .the tar acids may be blended back with the heavierfraction for use as creosote oil. Instead of fractionally cooling thevapors resulting from the distillation, the tarry oils may befractionally distilled by first removing the lighter oils and' then, onfurther'distilling, removing heavier oils.

'Various types of stills may be employed for carrying out thedistillation. Where thelighter tar or tarryoils are distilled bybringing them in direct contact with hot coal distillation gases,

the last-mentioned process of ractionally dis' lOb oils from the largevolume of gases which would necessarily be employed in thedistillation..

The tarry oils are rich in tar acids and naphthalene as compared withtotal tar and the distillate from such tarry oils will give a high yieldof naphthalene and tar acids. The heavy tar from the collector main iscorrespondingly low in tar acids and naphthalene. This tar is relativelyrich in free carbon and also in heavier oils and lower in the lightestoils. These properties are desirable in a road tar.

The invention will be further described in connectionwith theaccompanying drawings, but it is intended and is to be understood thatit is not limited thereto.

Fig.4 1 is a plan view of a coke oven plant equipped for carrying outthe invention;

Fig. 2 is an elevation partly in cross-section of the apparatus shown inFig. 1; and

Fig. 3 is a flow sheet representing various products which may beproduced according to the invention.

In the drawings 5 is a'coke oven battery, the ovens of which areconnected through theuptake pipes and goose-necks 6 with the collector'ist J condensers 12, 13. The tar from the collector main is drawn offthrough'the center-box to a. decanter 14 from which the tar is collectedin iii! 'Ari

theI tank 15. The cooling in the collector main is regulated by theproper adjustment of the amount of cooling medium admitted through thesprays in the goose-necks and the collector main, the insulation ornon-insulation of the collector main, etc. According to this inventionthe collector main operation is so controlled that the heavy tarproduced in the collector main and drawn oif into the tank 15 may beused for a road tar without distillation to remove lower boilingconstituents.

jWhere the road tar is to be blended with gas house tar-or water-gas taror some other tar to produce a blended road tar of desiredcharacteristics, this other tar may be mixed with the ammonia liquorsprayedl through the sprays 8 and 9, or the tar may be delivered with orwithout ammonia liquor to the-ends of vthe collector main and flushedthrough the bottom of the collector main or at one end of the collectormain and withdrawn from the other end. In such a case a blended productof higher free carbon content, suitable for use in road construction maybe obtained directly from the collector main.

The gases leaving the collector main are cooled in the condensers l2, 13and this cooling may be by the ammonia liquor sprays 16 or other meanssuch as' indirect cooling means may be employed. Where the gases aresprayed with ammonia liquor or are cooled below the dewpoint of thegases for ammonia liquor, the tarry arated from the ammonia liquor inthe decanter and will be separately collected as in 18. Several tarryoil fractions may be Arecovered by fractional cooling of the gasesandthese tarry oil fractions may be separately distilled. According tothe invention, at least one of the tarry oil fractions is distilled.

An exhauster is shown at 19 for drawing the gases through the system,and means for the recovery of ammonia and light oils is located beyondthe exhauster.

The tarry oils from the condensing system may be distilled in a pipecoil still or any other suitable type of still. The drawings providemeans for distilling the tar by the heat of the gases from selectedovens of the battery. 'I'he selected ovens are provided with uptakepipes and goose-necks 25 located at the `back of these ovens andconnecting with the hot gas lheader 26. By the proper manipulation ofvalves in the uptake pipes and goose-necks 25 and the uptake pipes andgoose-necks 6, the gases from these selected ovens may bedirected eitherto the' collector main 7 or through the header v26 into the still 27.

Within the still is a roll 28 which is located at one side of the stilland driven by the motor 29 at a speed of 900-1200 R. P. M. The tar isdistilled within the still and the pitch produced is withdrawn throughthe. trap 30 and the levelling arm 31. The level of tar within the stillis regulated by the position of the levelling arm 3l. Where a highmelting point pitch is produced, for example a pitch with a meltingpoint in the neighborhood of 400 or higher, the pitch as it comes fromthe` still is advantageously .sprayed with water from the line 32 in thetrough 33 s'o'that it is chilled and granulated from the undistilled tarresidue.

and is delivered to the storage bin 34v in the form of hard granules.

The hot gases passing from the ovens through the header 26 and the still27 pass up through the tower 28 and thence to the condenser or heatinterchanger 29. The gases are partially cooled in the heat interchangerand then passy to the condenser 53, and thence to an exhauster and meansfor the recovery of ammonia and' light oils, which may -be the exhauster19, and the same means for. the recovery of ammonia and light oils asthat employed for treating the gases collected in the collector main7and passed through thecross-over main 11 and the condensers l2, 13.

The tarry oil which is to be distilled may be fed directly to the stillor it may be fed through a nozzle, such as the nozzle 35, in the tower28. Bailies 36 and 3,7 below and above the nozzle tend to bring the tarsprayed in through the nozzle 35 into intimate and prolonged contactwith the hot gases and to remove entrained particles of spray from thegases. The tar which is partly distilled by the hot gases in the towercollects in the bottom of the tower and is advantageously passed throughthe line 38 to the end of the still at which the hot gases enter thestill. The gases and tar thus pass through the still in a concurrentdirection and the tar is distilled to pitch. By properly regulating thespeed of the rotation of the roll and the depth to which it dips intothe tar, an intense spray of tar may be produced within the gases in thestill so that the gases are detarred. The gases:V

leaving the still are tl'ren substantially clean gases and on coolingclean oils will be obtained.

According to a preferred method of carrying out this invention, thetarry oil from the tank 18 is pumped by the pump 40 throu'gh the line 41and in the condenser or heat interchanger 2'9 this tarry oil is broughtinto indirect contact with the' hot gases and vapors leaving the still.In this heat interchanger the tar is heated and partially distilled.From the ,heat interchanger the tar is brought'into the vapor chamber,42 in which/the vapors produced are separated The vapors pass throughthe main 4 3' to the condenser 44. This may' bel a condenser of thedirect orjindirect.

type in which the vapors of lower`boiling range distilled from the tarin the heat interchanger 29 land separated in th vapor box 42 are con-vdensed. The clean oils produced are drawn oi into the receiver* 45. v

The distillation residue from the vapor chamber 42 is pumped to thespray nozzle 35 in the tower 28 thru the line 46 by the pump 47. Thispartly distilled tar is further distilled by contacting with the gasesand vapors in the tower 28 and is heated and then .passes into the stillwhere it is further distilled. vAccording to a preferred method ofoperatingwa high melting polntpitch, for example, a pitch with ameltling point of 400 F. isproduced, and drawn off boiling constituentsis distilled within the still L 27, and the gases and vapors of higherboiling constituents pass from the still thru the main 50 into` thecondenser 29 Where higher boiling clean'oils are condensed by indirectcontact with the tarryoil. The heavy clean oil which sepa- 1.50

The-

With Fig. 3.

rates in this condenser 29 is withdrawn into the receiver 51. Thepartially cooled gases and vapors pass from the condenser 29 thru themain 52 to the condenser 53 where further clean oils are separated anddrawn oif into the receiver 54. `Owing to the fact that the lowerboiling constituents of the tarry oils are removed before the tarry oilsare brought into direct contact with the gases, the cooling in thecondensers 29 and 53 need only be such as to removehgher boiling oils.The loss of low boiling constituents in the gases is low and the yieldof oils is thereforev high. A yield of' 80-85 or 90% lof oil may beobtained..

In the operation of a coke oven battery in order to produce a tar suitedfor use Ias a road tar, 60-65% of the tar may be separated in thecollector main. The remaining 40-35% will be collected from thecondensers as tarry oil. This tarry oil product may be distilled toproduce '80-85% oil, and 20-15% of a high melting point pitch will beobtained. The oil yield may therefore be, for example, 29.75-32% of thetotal tar and the pitch will be the balance or 5.25-8%.

The yield of products obtained will. depend upon the length of thecoking cycle in the ovens, the temperatures employed, etc. The aboveexample is merely illustrative. A further discussion of possibleproducts, which is also merely illustrative, is given below inconnection The percentages of the various products employed and the'percentage yields are not shown in Fig. 3 since these figures aredependent upon many variables and Will vary from battery to battery.

The gases from vthe battery a are partially cooled to produce a heavytar b and tarry oil c. The tarry oil is .distilled to produce pitch dand one or more clean oil distillates -are obtained as, for example, theheavier-oil fraction e and the lighter oill fraction f. --The lighteroil fraction may be extracted for tar acids g and then chilled for therecovery, of naphthalene h. The neutral oil i which remains may beblended with the heavier oil e and with tarry oil c or heavier tar b toproduce creosoting composition j. The products from the tarry oildistillation, according to a preferred method of I operation, aretherefore the pitch d, naphthalene h, tar acids g and creosotingcomposition i. The heavy tar b is blended with gas-house tar 7c to giveroad tar l.

As an alternative arrangement, the neutral oil i may be used for Dieseloil. It may be blended With heavier oil e to produce a clean creosoteoil. It may be used to cut back tar or pitch and the blended mixtureburned for fuel.

Instead of blending the heavier tar and tarry oil produced from theoperation of a coke oven battery, the heavy tar and tarry oil areseparately collected, according to this invention,

' and the tarry oil is distilled and one or more .marketable productsmay bel produced. According to the preferred method of operation, theoperation of the collector main is so adjusted that the tar produced inthe collector main is suitable for use directly as road tar or issuitable for blending withV a tar of higher free carbon content, such asgas-house tar, or with a tar such as water-gas tar to produce road tarhaving desired characteristics.. In this manner the tar from thecollector main may be used for road treating purposes Without beingdistilled` References to pitch melting points referto melting pointsdetermined by the method decollector main to separate a tarry oiltherefrom v and distilling the tarry oil.

2. The method of treating hot coke oven gases, which comprisescollecting the gases in a collector main while still hot, subjectingthem to regulated cooling in the collector main, cooling the gasesleaving the collector main to separate tarry oils therefrom, distillingthe tarry oils to obtain a heavier clean oil fraction and a lighterclean oil fraction, extracting the lighter clean oil fraction for acidsand blending the resulting neutral oil with the heavier clean oilfraction and a tar condensed directly from the gases to produce acreosoting composition.

3. The method of treating hot coke oven gases, which comprisescollecting the gases in a collector main while still hot, subjecting thegases to regulated cooling in the collector main, further cooling thegases as they leave the collector main to separate tarry oils containingtar acids and naphthalene therefrom, and distilling the tarry oils toproduce a pitch with a melting point in the neighborhood of 400 F.,fractionally cooling the distillate to produce a. heavier oil and alighter oil, chilling the'lighter oil to separate naphthalene andextracting it to obtain tar acids.

4. The method of treating hot coke oven gases, which comprisescollecting in a collector main the gases from a plurality of ovens inwhich coal is distilled while the gases are still hot, subjecting thegases to regulated cooling in the collector main to separate a heavytar, cooling the gases leaving the collector main to separate tarry oiltherefrom, separately collecting the tarry oil, passing the vgases fromother ovens of the batdsery thru a still While still hot, and bringingthe tarry oil separately into intimate contact with the gases in thestill whereby the tarry oil is distilled and pitch is produced.

5. The method of treating hot coke oven gases, whichcomprises'collecting the gases from a plurality of ovens in a collectormain at substantially the temperature at which they leave thev ovens,subjecting the gases to regulated cooling in the collector main toproduce a road tar, cooling the gases leaving the collector main toseparate. tarry oil therefrom, passing the gases from selected ovens ofthe battery thru a still, bringing the gases and vapors from the stillinto indirect heat interchange relation with the tarry oil whereby thetarry oil is heated above the boiling point of its lower boilingconstituents, separating the vapors distilled from the tarry oil andcooling them to obtain a cleanvoil of low boiling range, furtherdistilling the tarry oil by bringing it into direct contact withthe hotgases in the still, whereby pitch is produced and the gases and vaporsresulting from the distillation are employed for heating and partiallydistilling the tarry oil by being brought into indirect heat interchangerelation therewith.

6. The method of treating hot coke oven gases which comprises collectingthe gases from the ovens in a collector main at substantially the veyingthe heated tarry oil from the heat interchanger to the vapor chamber, acondenser for temperature at which they leave the ovens sub-g coolingthe gasesl leaving the vapor chamber,

jecting the, gases to regulated cooling in the collector main to producea road tar, cooling the gases leavingithe collector main to separatetarry oil therefrom, passing the gases from selected ovens of thebattery through ai still, bringing the gases and vapors from the stillinto indirect heat interchange relation with the tarry oil, whereby thetarry oil is heated above the boilingv point of its lower boilingconstituents, passing the heated tarry oil to a vapor box, separatingvapors of lower boiling constituents from the undistilled residue,cooling these vapors to obtain a clean oil of low boiling range,distilling the undistilled residue by bringing it into direct contactwith the hot gases in the still whereby the undistilled residue isdistilled and the gases and vapors resulting from the distillation areemployed for heating the tarry oil by being brought into indirect heatinterchange relation therewith.

'7. In connection with a coke oven battery a gas collector main, aseparate receiver for the heavy tar produced in the collector main, acondenser for cooling the gases leaving the collector main, a separatetarry oil receiver. for the condensate from the condenser, a still,means for passing gases from a plurality of ovens through the still, asecond still comprising a heat interchanger for cooling the gases andvapors leaving the iirst still and for heating the tarry' pil thereby,means for separately conveying the tarry oil vthrough the second stillin indirect heat interchange relation with the gases and vapors passingtherethrough, a cooler for condensing vapors distilled from the tarryoil in the second still, and' means for conveying the distillationresidue of the tarry oil to the rst still.

8. In connection with a coke oven battery, a gas collector main, aseparate receiver for the heavy tar produced in the collector main. acondenser for cooling the gases leaving the collector main, a separatetarry oil receiver for the condensate. from the condenser, a still,means for passing gases froma plurality of ovens through the still, aheat interchanger for cooling the gases and vapors leavingvthe still,means for conveying the tarry oil through the heat interchanger inindirect heat interchange relation with the gases and vapors passingtherethrough, a vapor chamber, means for conand means for conveyingresidue from the vapor chamber to the still.

9. The method of producing road tar which comprises bringing gas housetar into direct contact with coke oven gases as they are cooled in thecollector main of a coke oven battery and regulating the cooling andamount of gashouse tarblended with tar from the gases so as to produce ablended tar product with a melting point between and 110 F.

10. The method of producing road tar which comprises bringing gas housetar into contact 90 with hot coke oven gases resulting from thedestructive distillation of coal in coke ovens as the gases are cooledin the collector main of a coke oven battery and regulating the coolingand the amount of gas house tar blended with tar from the gases so as toproduce a blended tar productwith a melting point between 90 and 115 F.

11. The method of treating coke oven gases which comprises collectingthem in a gas collector main and then cooling them in coolers andseparating from the gases between the time they leave the oven and thetime they enter coolers, tarry constituents which together have amelting point between 90 and 115 F. 105 A 12. 'I'he method of treatingcoke oven gases resulting from the destructive distillation of coal incoke ovens which comprises fractionally cooling them so as to separatefrom the gases as one fraction tarry constituents with a melt- 11( ingpoint between 90 and 115 F.

13. The method of treating coke oven gases which comprises cooling coaldistillation gases resulting from the destructive distillation of coalin coke ovens which comprises collecting the Agases from a plurality ofcoke ovens and col-

